Generally, giant magneto-resistance (GMR) elements for detecting presence or absence of magnetic field are widely known. The phenomenon that an electric resistance increases when a magnetic field is applied, is called as magneto-resistive effect. Although the resistance change of a common substance would be several percent, the resistance change of such GMR element reaches several tens of percent. For this reason, the GMR elements are widely used for recording heads of hard disks.
FIG. 1 is a perspective view illustrative of the operation principle of a conventional GMR element, and FIG. 2 is a partial cross-sectional view of FIG. 1. In the drawings, a reference numeral 1 denotes an antiferromagnetic layer, a reference numeral 2 denotes a pinned layer, a reference numeral 3 denotes a Cu layer (spacer layer), and a reference numeral 4 denotes a free layer. A magnetization direction of a magnetic material changes electronic spin scattering, and changes a resistance. In other words, the change of the resistance is represented by ΔR=(RAP−RP)/RP (where RAP: when magnetization directions on upper and lower sides are not parallel, and RP: when magnetization directions on upper and lower sides are not parallel).
As for the magnetic moment of the pinned layer 2, the direction is fixed by magnetic coupling with the antiferromagnetic layer 1. When the direction of the magnetic moment of the free layer 4 changes due to leakage field, the current flowing through the Cu layer 3 changes, and a change of the leakage field can be detected.
FIG. 3 is a schematic diagram illustrative of a stack of the conventional GMR element. In the drawing, a reference numeral 11 denotes an insulating film, a reference numeral 12 denotes a free layer, a reference numeral 13 denotes a conductive layer, a reference numeral 14 denotes a pinned layer, a reference numeral 15 denotes an antiferromagnetic layer, and a reference numeral 16 denotes an insulating film. The free layer 12 is a layer in which a magnetization direction rotates freely, and is made of NiFe or CoFe/NiFe. The conductive layer 13 is a layer in which a current flows and the electrons are scattered dependent on their spin, and is made of Cu. The pinned layer 14 is a layer in which a magnetization direction is fixed in a specific direction, and is made of CoFe or CoFe/Ru/CoFe. The antiferromagnetic layer 15 is a layer for fixing the magnetization direction of the pinned layer 14, and is made of PtMn or IrMn. The insulating films 11 and 16 are made of Ta, Cr, NiFeCr, or AlO. The pinned layer 14 may use a self-bias structure instead of the antiferromagnetic layer.
FIG. 4 is a plain view illustrative of a pattern shape of a conventional GMR element. The GMR element has a sensitive axis in the magnetization direction of the pinned layer 14. When there is no magnetic field, the magnetization direction of the free layer of the GMR element is the longitudinal direction of the GMR element. When the magnetic field is inputted in the direction of the sensitive axis, the magnetization direction of the free layer is changed depending on the magnetic field. Thus, the resistance of the GMR element is changed.
Recently, an electronic compass is widely used in a mobile phone or the like, and includes a magnetic sensor capable of detecting the terrestrial magnetism and outputting resolved three orthogonal axis components of the magnetic signal. By calculation using the three output signals obtained by the magnetic sensor, the electronic compass obtains the direction of the terrestrial magnetism precisely.
Now, a magnetic sensor detecting the terrestrial magnetism and outputting resolved three orthogonal axis components of the magnetic signal is proposed in PTL 1, for example. This sensor includes a two-axis magnetic sensor unit configured to detect terrestrial magnetism components in two axis directions (X axis and Y axis) which are set parallel to a substrate surface and perpendicular to each other, and a magnetic flux concentrator concentrating a magnetic field in the perpendicular direction (Z axis) to the substrate surface including the two axes and disposed on the two-axis magnetic sensor unit. Coils are formed on a magneto-resistance element, and the magnetization direction is controlled by a magnetic field generated by a current flowing into the coils, and the magnetic flux concentrator converts the magnetic field direction to detect the X-, Y-, and −Z magnetic fields on the substrate.
In addition, open/close switch and rotation detector widely used in a mobile phone or the like are proposed in PTL 2, for example. A magnetic sensor and a magnet are used in detection, and a hinge is made of nonmagnetic material so as to prevent an erroneous detection of the magnetic sensor.
In addition, for example, a technique described in PTL 3 relates to a magnetic recording head using a GMR element, and PTL 3 discloses a spin-valve magneto-resistance (MR) sensor including a pinned layer which has been improved so that the magneto-static coupling of a free layer is the minimum. A stack of the free layer and a pinned layer is illustrated in PTL 3.
In addition, a magnetic sensor using a Hall element is proposed as an electronic compass for detecting a three-dimensional magnetic field. Hall element can detect a magnetic field perpendicular to a substrate where the Hall element is disposed, and can detect a magnetic field in Z direction when the element is disposed on the substrate surface. For example, PTL 4 describes that Hall elements are disposed in a cross shape, i.e. on the upper and lower sides, and right and left sides with respect to a symmetry center under a circular magnetic flux concentrator. By utilizing the fact that a horizontal magnetic field is converted into a magnetic field perpendicular to the substrate at an end of the magnetic flux concentrator, not only the perpendicular magnetic field but also the horizontal magnetic field are detected, so that the magnetic fields in X-, Y-, and Z-axis directions can be detected on the substrate.
In addition, for example, a technique described in PTL 5 relates to a magnetic sensor having magneto-resistive effect elements disposed so as to intersect with one another in three dimensional directions on a single substrate. The magnetic sensor uses the magneto-resistance element including a pinned layer and a free layer. Then, PTL 5 describes the magnetic sensor with high sensitivity measuring a magnetic field in a direction perpendicular to a surface of the magnetic sensor. It is proposed that X-, Y-, and Z magnetic fields are detectable on the substrate, by performing vector decomposition for the Z magnetic field applied in the vertical direction which is originally undetectable, by disposing the magneto-resistance element detecting a horizontal magnetic field on a slope.
In addition, for example, PTL 6 describes a GMR element formed to have one polygonal line pattern on a substrate.